A structure that a shielding plate is disposed at the center portion of one board accommodated in a case is known in Patent Literature 1. The following descriptions are referred in Patent Literature 1: an optical receiving IC and an amplifier IC are mounted on one board, which has right and left notches at the center section between the optical receiving IC and the amplifier IC; a notch is formed at a portion facing a signal line on the bottom face of the shielding plate in order to avoid abutting against the signal line provided on the board; and the shielding plate is inserted so as to be engaged with the board through the whole thickness at the notch parts. A lid is disposed on the case and the shielding plate.
Further, a power semiconductor module is described in Patent Literature 2: a protrusion is disposed on the backside of a lid plate to press a control circuit printed board from the upper side so that the printed board is suppressed from shifting up and a stress generated in a solder joined part where a lead pin is connected to the printed board is relaxed.
Moreover, as a reference of a terminal, a semiconductor module including a plurality of semiconductor chips, bonding wires, a resin case, and external lead-out metal terminals (hereinafter, metal terminals), which are insert-molded in the resin case, is described in Patent Literature 3. The metal terminals are insert-molded at an outer peripheral frame of the resin case to enlarge an inside space of the case, and wiring is carried out by using only bonding wires between two parts such as an insulating circuit board, a semiconductor chip and a terminal so the metal terminal is not joined directly with solder on the insulating circuit board in the structure. The structure demands that the metal terminal is surely fixed with the resin case. If the metal terminal is not fixed properly on the resin case, connection failure may occur when wire bonding is performed to the metal terminal. Then, in conventional art, the fixing between the metal terminal and the resin case has been strengthened by providing convex parts protruding outside at the bottom part of the metal terminal bent in an L-shape, and forming the corresponding part of the resin case in a step-wise in order to support the metal terminal surely at the bottom part where wire bonding is performed.